The present technology relates to a waveguide that transmits a signal between transmission lines, an interposer substrate including the waveguide, a module, and an electronic apparatus.
Mounting technology utilizing a relay board which is called an interposer is generally known as a technology used when an LSI (Large Scale Integration) chip having a fine pad pitch is to be mounted on a mounted substrate which is wide in pitch. Although the interposer is made of a dielectric such as a resin and a ceramic in many cases, a silicon interposer which is allowed to cope with finer pitch by using a silicon substrate and semiconductor process that allows micromachining attracts attention today.
In the above-mentioned silicon interposer, a front surface and a back surface of the silicon substrate are electrically connected to each other by a through electrode which is called a TSV (Through Silicon Via). Thus, a signal is transmitted from the front surface to the back surface of the silicon substrate. However, this silicon interposer has a disadvantage in that, in millimeter-wave bands and high frequency regions exceeding the millimeter-wave bands, return loss (or reflection loss) is increased due to impedance mismatching between a transmission line on the front surface of the substrate and the TSV.
A coaxial TSV that achieves impedance matching with a surface wiring by forming a coaxial form in a vertical direction of the silicon substrate is reported as one measure of eliminating this disadvantage (see, for example, Soon Wee Ho et al., IEEE Electronic Components and Technology Conference (ECTC), 2008).